| 摘要 |
PROBLEM TO BE SOLVED: To attain both a high performance and safety in data communication between a controller and a process I/O unit. SOLUTION: The device is provided with a circuit which generates and adds a CRC (Cyclic Redundancy Check) to a transmitted data of the controller and the process I/O unit, a circuit which checks the CRC of a received data, and a status register which selects operation modes of operation or stop of a CRC generation and a check function and shows CRC errors in each device, and inconsistency of the operation mode of a transmitter and a recipient of the data. It also performs a check of the CRC in a relay communication device. When two or more relay communication devices exist, the CRC for transmission between relay communication devices is additionally added, the CRC check result in each device of the controller, the relay communication device, and the process I/O unit is reflected in the status register, the soundness of the data between terminals is checked, the data having errors generated in a transceiver process is prevented from being used, and the device is prevented from a malfunction. COPYRIGHT: (C)2007,JPO&INPIT
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